Tetradecanal

Lyophilized preparations of enzymes were produced in the Laboratory of Nanobiotechnology and Bioluminescence at the Institute of Biophysics, Siberian Branch, Russian Academy of Sciences (Krasnoyarsk, Russia). Luciferase (Luc) Photobacterium leiognathi (0.5 mg) was purified from the recombinant strain of Escherichia coli, while NAD(P)H:FMN-oxidoreductase (Red) (0.15 units) from luminous bacteria Vibrio fischeri. Lactate dehydrogenase (LDH) from rabbit muscles was procured from Sigma (Type XI, catalog No. L1254, 5000 units). NAD⁺ (AppliChem, Darmstadt, Germany), and DL-lactic acid (Sigma, Steinheim, Germany) were used as substrates of LDH; FMN (Serva, Heidelberg, Germany) and tetradecanal (Merck, Steinheim, Germany) were used as substrates for the Red + Luc enzyme system. To prepare the R + L enzyme solutions, 5 mL of potassium phosphate buffer (pH 7.2) was added to a vial containing the enzymes. For preparing the LDH enzyme solution, 0.5 mL of potassium phosphate buffer (pH 7.2) was added to a vial. The tetradecanal solution [0.0025% (v/v)] was prepared by mixing 50 μL of 0.25% (v/v) ethanol solution of aldehyde and 5 mL of 0.05 M potassium phosphate buffer (pH 7.2). The NAD⁺ solution was prepared in a 0.05 M potassium phosphate buffer (pH 7.2). The samples of FMN and lactic acid were dissolved in distilled water.